This application is a national stage of PCT/FR 98/01109 filed Jun. 2, 1998 and based upon French national applications 97.07000 of Jun. 2, 1997 and 97.10105 of Aug. 1, 1997 under the International Convention.
The present invention relates to an apparatus for neutralizing radio telephones in spaces where their use is prohibited or annoying.
At present, the number of radio telephones is becoming very large. Their automatic ringing or calls are of such a nature as to annoy the other people present in the same space or to disturb the operation of acoustic or electronic apparatuses.
By way of examples, the premises to be protected may be: aircraft, auditoria, cinemas, theaters, courtrooms, schools, hospitals, meeting rooms, conference rooms, restaurants, churches, etc.
Other spaces may be relevant, whether they be open (cemeteries, etc.) or enclosed (vehicles, trains, etc.). Protection must be affected selectively as a function of the choice of those responsible for these spaces and in compliance with the global radio telephony system.
The MOTOROLA document by Weiss and Muri, Vol. 13 of July 1991 uses a system with radio relays using different frequencies from those of the base transmitters. The Patent US WEST EP 0568824 requires special mobile telephones pre-programmed to identify the zones. Our invention does not use a system with different frequencies and is applicable to mobiles currently in service. The present invention also relates to other radio messaging apparatuses which possess a ringing tone, designated hereinbelow by the general name of radio telephones.
The present invention does not relate to mobile transmitters which could be used on an ad hoc basis for police or military purposes.
The object of the present invention is to deliberately neutralize radio telephones without the intervention of their users, by jamming or modifying the communications: reception and/or transmission.
We shall call the apparatus which is the subject of the invention a jammer even when it merely filters.
The present invention is based on a jamming apparatus having several options and levels of jamming and filtering. The principles of the invention are applicable to all analogue or digital radio telephony systems regardless of the systems or the standards: GSM, DCS, DECT, CT2, 3RP, PHP, PHS, PDC, AMPS, IS54, CDMA, UDPC, CDMA, DSSR, PCN, PCS, FPLMTS, UMTS, etc. with terrestrial or satellite transmitters.
According to a first variant, the present invention jams the reception of the call signals and of beacon paths.
The ringing of a radio telephone is triggered by the receiving of the individual code of the radio telephone via the airwaves.
The present variant uses the superposition onto these codes of an unidentifiable radio signal, on the same frequencies, thereby modifying the call codes which are no longer recognized by the destination radio telephones. The radio telephone will be regarded as inaccessible to the transmitter, and this will trigger a possible messaging. According to several variants, the jammer behaves as a transmitter with superposition on the radio signals so as to render them barely recognizable, either continuously, or intermittently, or as a filter by setting up a coded dialogue with the base stations.
This jammer must not disturb the communications in spaces which are not deliberately protected. The aim of the present invention is to restrict the volume to be jammed by adapting the power of the jamming signal as a function of the volume and of the nature of the materials of the walls of the premises to be protected, its angular coverage as well as the nature of the signals transmitted.
To restrict the jamming and its power, the present invention, according to one of its characteristics, will comprise a receiver which will make it possible to measure the power of the receptions and thus, to adapt the jamming in terms of power and nature. One variant makes it possible also to detect the response of local telephones so as to jam their signal at certain specific moments (intermittent).
In certain cases, the power may be less than 5 mW. According to another method, the jammer will detect and/or neutralize the radio telephones when passing into specific geographical sites: doors, etc. It will therefore be possible for the jammers to be active or passive depending on whether they include a receiver and a transmitter or only a transmitter for each system to be jammed.
Depending on their configurations, that will enable varied functionalities to be added to them:
switchover from ringing tone to buzzer,
storing of calls,
selective filtering of telephones according to chosen numbers, chosen sites, etc.
genuine local radio telephone switching office, able to constitute a genuine selective base station adapted to a restricted volume and for carrying out selective filtering as a function of numbers, of call type, etc. with certain analogies with current telephone switching offices.
To adapt the protection to large volumes or to volumes of any shapes, the combining of several apparatuses will be envisaged, likewise for the various standards. The radio telephone becomes operational again once it leaves the protected space, without intervention by the owner.
Messages will be displayed so as to forewarn the user of calls during his presence in jammed zones (option). In practice, a display will be able to forewarn of the protection of the premises on entry thereto and on exit therefrom.
Specifically, when the mobile telephone is used for important or urgent communications, the users must be forewarned and act under their responsibility. Several levels of jamming are envisaged: blocking of reception and/or blocking of transmission, depending on the choice of those responsible for the volumes to be protected.
The hardware which is the subject of the present invention thus consists, at least, of a housing containing a high-frequency transmitter (480,900,1800 Mhz . . . ranges depending on the standards used in the relevant country) with adjustment in terms of power and angular direction.
The transmission of the jamming signal is performed by scanning the frequency ranges used by the radio telephones. According to a first characteristic, the hardware which is the subject of the invention sends a unique periodic signal with frequencies corresponding to the receptions of the radio telephones. For the GSM900 system, for example, the jamming signal will consist of signals transmitted on the frequencies of the beacon paths for the site.
For all the other radio telephony systems present in the same premises, various frequencies will be used. It can also be transmitted on the search channel PCH more selectively, after detecting its frequencies. The call code is modified by this electromagnetic noise, the triggering of ringing does not occur.